What if an NPC got tired of being beaten, robbed, and killed as a daily routine? What if he started to see the world as a game player, rather than as an NPC? If you've seen the trailers, you know Ryan Reynolds is "Guy." What's not mentioned at all in the trailer(s) is that there's a lot of code behind that character - code that's the subject of a lawsuit in "the real world."
What makes the movie work is a good (and comedic) interpretation of the life of NPCs, and the game itself - combined with a couple other fairly interesting stories about software theft, AI, and romance. Wikipedia says "... compared ... favorably to a combination of action video games and science fiction films such as 'Ready Player One,' 'The Truman Show,' 'The Matrix,' 'Grand Theft Auto,' and 'Fortnite.'" For me, one of the down-sides was Reynolds being Reynolds: his comedy here is similar to his work in "Deadpool" and "Pikachu." Not that that's terrible: he's pretty funny. But it does feel a bit too familiar.
Overall though, it's a surprisingly successful send-up (and a bit of a tribute) of video gaming as a culture. And it's just ... charming. Surprisingly fun.
POSTSCRIPT: A minor quibble. In the trailer, Guy kisses Molotov Girl and then her player describes this to someone who says "there's no button for that," to which she replies "Oh, he found the button!" It's a great joke, but later Molotov Girl kisses Guy ... and how did she do that when there's no button for that?